package config

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"chub/internal/domain"
)

const currentVersion = 1

type Settings struct {
	ChromePath  string `json:"chromePath"`
	EdgePath    string `json:"edgePath"`
	DefaultDir  string `json:"defaultUserDataDir"`
	LogDir      string `json:"logDir"`
	CloseOnExit bool   `json:"closeOnExit"`
}

type Instance struct {
	ID        string            `json:"id"`
	Name      string            `json:"name"`
	Launch    domain.LaunchSpec `json:"launch"`
	UpdatedAt time.Time         `json:"updatedAt"`
}

type File struct {
	Version   int        `json:"version"`
	Settings  Settings   `json:"settings"`
	Instances []Instance `json:"instances"`
}

type Store struct{ path string }

func New(path string) (*Store, error) {
	if path == "" {
		return nil, errors.New("config path is required")
	}
	return &Store{path: filepath.Clean(path)}, nil
}

func DefaultPath() (string, error) {
	dir, err := os.UserConfigDir()
	if err != nil {
		return "", fmt.Errorf("resolve user config dir: %w", err)
	}
	return filepath.Join(dir, "chub", "config.json"), nil
}

func (s *Store) Path() string { return s.path }

func (s *Store) Load() (File, error) {
	data, err := os.ReadFile(s.path)
	if errors.Is(err, os.ErrNotExist) {
		return File{Version: currentVersion, Settings: DefaultSettings()}, nil
	}
	if err != nil {
		return File{}, fmt.Errorf("read config: %w", err)
	}
	var result File
	if err := json.Unmarshal(data, &result); err != nil {
		return File{}, fmt.Errorf("decode config: %w", err)
	}
	if result.Version == 0 {
		result.Version = currentVersion
	}
	if result.Version != currentVersion {
		return File{}, fmt.Errorf("unsupported config version %d", result.Version)
	}
	return result, nil
}

func DefaultSettings() Settings {
	return Settings{
		ChromePath:  `C:\Program Files\Google\Chrome\Application\chrome.exe`,
		EdgePath:    `C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe`,
		DefaultDir:  `C:\Users\Public\chub\profiles`,
		LogDir:      `C:\Users\Public\chub\logs`,
		CloseOnExit: true,
	}
}

func (s *Store) Save(value File) error {
	value.Version = currentVersion
	if value.Instances == nil {
		value.Instances = []Instance{}
	}
	data, err := json.MarshalIndent(value, "", "  ")
	if err != nil {
		return fmt.Errorf("encode config: %w", err)
	}
	if err := os.MkdirAll(filepath.Dir(s.path), 0o700); err != nil {
		return fmt.Errorf("create config dir: %w", err)
	}
	tmp, err := os.CreateTemp(filepath.Dir(s.path), ".config-*.tmp")
	if err != nil {
		return fmt.Errorf("create config temp: %w", err)
	}
	tmpName := tmp.Name()
	defer os.Remove(tmpName)
	if err := tmp.Chmod(0o600); err != nil {
		_ = tmp.Close()
		return fmt.Errorf("protect config temp: %w", err)
	}
	if _, err := tmp.Write(data); err != nil {
		_ = tmp.Close()
		return fmt.Errorf("write config temp: %w", err)
	}
	if err := tmp.Sync(); err != nil {
		_ = tmp.Close()
		return fmt.Errorf("sync config temp: %w", err)
	}
	if err := tmp.Close(); err != nil {
		return fmt.Errorf("close config temp: %w", err)
	}
	if err := replace(s.path, tmpName); err != nil {
		return err
	}
	return nil
}

func replace(target, temp string) error {
	backup := target + ".bak"
	_, statErr := os.Stat(target)
	if statErr == nil {
		_ = os.Remove(backup)
		if err := os.Rename(target, backup); err != nil {
			return fmt.Errorf("backup config: %w", err)
		}
	}
	if err := os.Rename(temp, target); err != nil {
		if statErr == nil {
			_ = os.Rename(backup, target)
		}
		return fmt.Errorf("replace config: %w", err)
	}
	_ = os.Remove(backup)
	return nil
}